The present invention relates to towel winder systems, and more particularly to a system and method for controlling the outside diameter and sheet count of a towel roll during the winding operation.
Automated towel winder systems are used to wind rolls of paper, such as paper towels and toilet tissue. These systems roll and perforate thousands of sheets of paper every few minutes. A towel winder system may wind 10-15 rolls of paper concurrently. Typically, a spindle driven by a spindle drive rotating at a predetermined speed profile is employed to wind a roll of paper on a core, until the roll reaches a predetermined outside diameter. It is desired that each completed roll have a predetermined reliable outside diameter and an exact sheet count of paper. However, obtaining reliable outside diameters and exact sheet counts is a highly complex process. It is important to achieve roll uniformity for packaging and shipping in addition to producing rolls at consistent cost. For example, a harder roll having the same diameter as a softer roll means that the harder roll has more paper. Inconsistencies among rolls for a given lot result in non-uniformity in costs and quality not to mention packaging and shipping problems. Therefore, a goal in producing paper rolls is to be able to achieve a uniform sheet count and roll diameter for a batch of rolls.
In the past, efforts to achieve exact sheet count among rolls often involved utilizing machined mechanical cams having linkages to electrical potentiometers or to outer mechanical positioners coupled to electrical signal transducers to produce spindle speed profiles. The spindle speed profiles were used to reduce speed of a rotating spindle on which paper was rolled during winding thereof as the outside diameter of the roll increased. Through a combination of volume and experience a speed reference was measured and these results were used to machine different cams for various desired roll parameters. Pre-selected cams could then be mounted to the machine to produce a speed profile for a particular production run. Over the years, theoretical and empirical information embedded in the cams and electrical signals produced by the cams were used to establish look up tables-this was accomplished by plotting many points on the cam that reflect electrical signals. This hard cam data was then employed to produce a programmed software speed profile referred to as a soft cam. However, both the soft cams and the mechanical cams have a limited number of profile points resulting in inconsistencies from roll to roll. Additionally, the speed profiles are based on information formulated from previously wound rolls and not the lot currently being produced, which may experience slightly different environmental conditions.
Accordingly, there is a strong need in the art for a system and method that provides improvements over conventional techniques for winding rolls to achieve a desired diameter and sheet count.
The present invention relates to a system and method for developing speed and rotation count profiles for controlling the spindle drive on a towel winder system for winding rolls of paper, such as tissue or towel. The system and method monitors accumulated paper sheet length metered onto the winding spindle to control desired sheet count and finished roll dimension data. The system and method utilizes accumulated paper sheet length data and desired finished roll data to calculate an instantaneous diameter. The instantaneous diameter calculation includes determining an effective thickness of the roll (e.g., sheet thickness and entrapped air) based on two forms of calculating finished roll cross-sectional area. The system and method also includes monitoring the actual line surface speed. The instantaneous diameter and actual line surface speed are used to generate a speed reference signal and an inertia control signal. An outer control loop can be employed to trim the speed reference signal so as to improve controlling revolution count.
In one aspect of the invention, a method is provided for controlling a spindle drive during winding of a towel roll on a towel winder system. The method comprises the steps of monitoring at least one real time parameter relating to winding of the towel roll and determining a speed spindle component that adjusts the spindle drive speed based on changes of the at least one real time parameter.
In accordance with another aspect of the invention, a method is provided for developing a speed profile for a spindle drive during winding of a towel roll on a towel winder system. The method comprises the steps of evaluating an effective thickness of the towel roll, monitoring an accumulated towel length during winding of the towel roll, determining an instantaneous diameter of the towel roll based on the effective thickness of the roll and the accumulated towel length, and determining a spindle speed component that adjusts speed of the spindle drive based on changes in the instantaneous diameter.
In accordance with yet another aspect of the invention, a system is provided for controlling a spindle drive during winding of a towel roll on a towel winder system. The system includes an instantaneous diameter component adapted to monitor accumulated towel length and generate an instantaneous diameter value, and a spindle speed component adapted to receive an instantaneous diameter value from the instantaneous diameter component and generate a spindle speed reference value.
Another aspect of the invention relates to a system for controlling a spindle drive during winding of a towel roll on a towel winder system. The system comprises a processor, a memory operatively coupled to the processor and at least one sensor operatively coupled to the processor, the at least one sensor adapted to monitor a real time parameter relating to winding of the towel roll, wherein the processor receives digital data relating to the real time parameter and generates a spindle speed reference value.
In accordance with an alternate aspect of the invention, a system is provided for controlling a spindle drive during winding of a towel roll on a towel winder system. The system comprises means for monitoring at least one real time parameter relating to winding of the towel roll and means for determining a speed spindle component for adjusting spindle drive speed based on changes of the at least one real time parameter.
In accordance with yet another aspect of the invention, a tool is provided for determining speed values for a spindle drive used in winding of a towel roll on a towel winder system. The tool comprises a towel winder data spread sheet that allows for modification of basic product set up data. The towel winder data spread sheet is adapted to calculate a total length on a finished roll and an effective thickness of individual wraps. The towel winding data spread sheet is further adapted to calculate spindle speed based on entered machine speed. The towel winding data spread sheet is also adapted to calculate length of towel on a roll, the diameter of the roll and mandrel revolutions of the roll based upon number of sheets per roll.
To the accomplishment of the foregoing and related ends, the invention then, comprises the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative aspects of the invention. These aspects are indicative, however, of but a few of the various ways in which the principles of the invention may be employed and the present invention is intended to include all such aspects and their equivalents. Other aspects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings.